'Bitterly' definitions:

Definition of 'bitterly'

From: WordNet
adverb
With bitterness, in a resentful manner; "she complained bitterly"
adverb
Indicating something hard to accept; "he was bitterly disappointed"
adverb
Extremely and sharply; "it was bitterly cold"; "bitter cold" [syn: piercingly, bitterly, bitingly, bitter]

Definition of 'Bitterly'

From: GCIDE
  • Bitterly \Bit"ter*ly\, adv. In a bitter manner. [1913 Webster]